In Friedman U.S. Pat. No. 4,091,316 a method and apparatus is disclosed for avoiding vibrations and loss of synchronism of stepping motors. In the Friedman reference, a tachometer is used as a generator of actual values and a control circuit is used to control, i.e. modulate, the phase angle of the control pulses of the stepping motor.
The object of the present invention is to provide a stabilizing arrangement for a stepping motor to accomplish the following:
to operate one- or multiphased stepping motors stably within their parametric resonance bands without using probes, for example hall-probes, induction coils, expensive tachometers, mechanical or optical probes and their associated couplings. Preferably, the stabilization is without dead time, is relatively fast and independent of load, i.e. the stabilization bears easily changes of load from one to one hundred, PA1 to work in an extremely large speed-range from zero to 35,000 revolutions per minute PA1 to improve the efficiency of the stepping motor when the power output is high and thus render possible high mechanical power PA1 to provide a stepping motor that is independent of the particular type of sequence generator, e.g. constant voltage, constant current, chopper, bilevel or L/R control, including FS, HS, and microstepping mode. Is independent of the phase number: 1, 2, 3, n phases PA1 to stabilize the stepping motor when its movement is steady or accelerated, PA1 to provide a stabilizing arrangement whose price is reasonable compared to the price of the stepping motor, PA1 to operate two or more parallel switched stepping motors with one single stabilizing apparatus.
A stabilizing arrangement which achieves the forgoing objectives will render possible the use of smaller, i.e. cheaper stepping motors and will enable the use of stepping motors for purposes, where until now only stable use of D.C. motors was possible. Preferably, the stabilizing apparatus is built so that it can be switched as an interface-circuit between the normally already existing elements of the control apparatus of a stepping motor without the control apparatus having to be substantially changed.